The conventional plunger, which consists of a resilient collapsible cup attached to the end of a handle, is well known and widely used. The open lower end of the cup is submerged in the water in sealing engagement about a drain and the cup is pumped alternately down and up to create hydraulic pressure on a clog lodged in the drain pipe.
Generally speaking, plungers of the prior art are often too slow and ineffective in achieving the desired result. Despite the fact that many attempts at improvement have been made, there remains a need for a fast-acting, effective plunger which is simple in construction and operation.
The conventional plunger has been modified in a variety of ways to improve the pumping action or for various other reasons. Examples of prior art devices include those disclosed in U.S. Pat. Nos. 4,445,236 (Nadolny et al.), 4,238,860 (Dixon), 3,644,943 (Parodi fu Leonardo et al.), 2,846,698 (Tomlinson), 2,496,525 (Eggleston) and 1,734,206 (Fisch), and British Specification No. 20,066 (Cooper). However, there are practical problems in these and other plungers of the prior art.
The most commonly used plungers have the problem of applying an often unwanted updrawing pressure on the clog between downward clog-clearing strokes of the plunger. When the collapsed cups of such plungers reassume their normal cup-like shapes, excessively negative pressures are created and cause such updrawing.
Plungers of the prior art designed to reduce this undesirable reverse action, including various valved plungers, are too complex in construction and operation. There has been a need for a plunger of simple and reliable construction overcoming this problem.
Another drawback of prior art devices is the difficulty sometimes encountered in controlling the degree of hydraulic pressure to be applied to the clog. Sometimes, when greater manual pressure is applied to the plunger, the water trapped within the collapsing cup in the toilet bowl or other container will burst unexpectedly out of the cup causing agitation in the bowl to such an extent that the typically waste-laden water may splash or spill out. This, of course, is very undesirable.
There is a need for an improved plunger minimizing or avoiding this problem. There is a need for an improved plunger allowing easy variation, particularly increases, in the degree of hydraulic pressure applied to the clog without greatly increasing the risk of uncontrollable water bursts, splashing and spilling. There is a need for an improved plunger having these advantages, and yet being simple and reliable in construction.